/* ----------------------------------------------------------------------
* Copyright (C) 2010 ARM Limited. All rights reserved.
*
* $Date:        15. February 2012
* $Revision: 	V1.1.0
*
* Project: 	    CMSIS DSP Library
* Title:	    arm_bitreversal.c
*
* Description:	This file has common tables like Bitreverse, reciprocal etc which are used across different functions
*
* Target Processor: Cortex-M4/Cortex-M3/Cortex-M0
*
* Version 1.1.0 2012/02/15
*    Updated with more optimizations, bug fixes and minor API changes.
*
* Version 1.0.10 2011/7/15
*    Initial Version
* -------------------------------------------------------------------- */

#include "arm_math.h"
#include "arm_common_tables.h"

/*
 * @brief  In-place bit reversal function.
 * @param[in, out] *pSrc        points to the in-place buffer of floating-point data type.
 * @param[in]      fftSize      length of the FFT.
 * @param[in]      bitRevFactor bit reversal modifier that supports different size FFTs with the same bit reversal table.
 * @param[in]      *pBitRevTab  points to the bit reversal table.
 * @return none.
 */

void arm_bitreversal_f32(
    float32_t* pSrc,
    uint16_t fftSize,
    uint16_t bitRevFactor,
    uint16_t* pBitRevTab)
{
	uint16_t fftLenBy2, fftLenBy2p1;
	uint16_t i, j;
	float32_t in;

	/*  Initializations */
	j = 0u;
	fftLenBy2 = fftSize >> 1u;
	fftLenBy2p1 = (fftSize >> 1u) + 1u;

	/* Bit Reversal Implementation */
	for(i = 0u; i <= (fftLenBy2 - 2u); i += 2u) {
		if(i < j) {
			/*  pSrc[i] <-> pSrc[j]; */
			in = pSrc[2u * i];
			pSrc[2u * i] = pSrc[2u * j];
			pSrc[2u * j] = in;

			/*  pSrc[i+1u] <-> pSrc[j+1u] */
			in = pSrc[(2u * i) + 1u];
			pSrc[(2u * i) + 1u] = pSrc[(2u * j) + 1u];
			pSrc[(2u * j) + 1u] = in;

			/*  pSrc[i+fftLenBy2p1] <-> pSrc[j+fftLenBy2p1] */
			in = pSrc[2u * (i + fftLenBy2p1)];
			pSrc[2u * (i + fftLenBy2p1)] = pSrc[2u * (j + fftLenBy2p1)];
			pSrc[2u * (j + fftLenBy2p1)] = in;

			/*  pSrc[i+fftLenBy2p1+1u] <-> pSrc[j+fftLenBy2p1+1u] */
			in = pSrc[(2u * (i + fftLenBy2p1)) + 1u];
			pSrc[(2u * (i + fftLenBy2p1)) + 1u] =
			    pSrc[(2u * (j + fftLenBy2p1)) + 1u];
			pSrc[(2u * (j + fftLenBy2p1)) + 1u] = in;

		}

		/*  pSrc[i+1u] <-> pSrc[j+1u] */
		in = pSrc[2u * (i + 1u)];
		pSrc[2u * (i + 1u)] = pSrc[2u * (j + fftLenBy2)];
		pSrc[2u * (j + fftLenBy2)] = in;

		/*  pSrc[i+2u] <-> pSrc[j+2u] */
		in = pSrc[(2u * (i + 1u)) + 1u];
		pSrc[(2u * (i + 1u)) + 1u] = pSrc[(2u * (j + fftLenBy2)) + 1u];
		pSrc[(2u * (j + fftLenBy2)) + 1u] = in;

		/*  Reading the index for the bit reversal */
		j = *pBitRevTab;

		/*  Updating the bit reversal index depending on the fft length  */
		pBitRevTab += bitRevFactor;
	}
}



/*
 * @brief  In-place bit reversal function.
 * @param[in, out] *pSrc        points to the in-place buffer of Q31 data type.
 * @param[in]      fftLen       length of the FFT.
 * @param[in]      bitRevFactor bit reversal modifier that supports different size FFTs with the same bit reversal table
 * @param[in]      *pBitRevTab  points to bit reversal table.
 * @return none.
 */

void arm_bitreversal_q31(
    q31_t* pSrc,
    uint32_t fftLen,
    uint16_t bitRevFactor,
    uint16_t* pBitRevTable)
{
	uint32_t fftLenBy2, fftLenBy2p1, i, j;
	q31_t in;

	/*  Initializations      */
	j = 0u;
	fftLenBy2 = fftLen / 2u;
	fftLenBy2p1 = (fftLen / 2u) + 1u;

	/* Bit Reversal Implementation */
	for(i = 0u; i <= (fftLenBy2 - 2u); i += 2u) {
		if(i < j) {
			/*  pSrc[i] <-> pSrc[j]; */
			in = pSrc[2u * i];
			pSrc[2u * i] = pSrc[2u * j];
			pSrc[2u * j] = in;

			/*  pSrc[i+1u] <-> pSrc[j+1u] */
			in = pSrc[(2u * i) + 1u];
			pSrc[(2u * i) + 1u] = pSrc[(2u * j) + 1u];
			pSrc[(2u * j) + 1u] = in;

			/*  pSrc[i+fftLenBy2p1] <-> pSrc[j+fftLenBy2p1] */
			in = pSrc[2u * (i + fftLenBy2p1)];
			pSrc[2u * (i + fftLenBy2p1)] = pSrc[2u * (j + fftLenBy2p1)];
			pSrc[2u * (j + fftLenBy2p1)] = in;

			/*  pSrc[i+fftLenBy2p1+1u] <-> pSrc[j+fftLenBy2p1+1u] */
			in = pSrc[(2u * (i + fftLenBy2p1)) + 1u];
			pSrc[(2u * (i + fftLenBy2p1)) + 1u] =
			    pSrc[(2u * (j + fftLenBy2p1)) + 1u];
			pSrc[(2u * (j + fftLenBy2p1)) + 1u] = in;

		}

		/*  pSrc[i+1u] <-> pSrc[j+1u] */
		in = pSrc[2u * (i + 1u)];
		pSrc[2u * (i + 1u)] = pSrc[2u * (j + fftLenBy2)];
		pSrc[2u * (j + fftLenBy2)] = in;

		/*  pSrc[i+2u] <-> pSrc[j+2u] */
		in = pSrc[(2u * (i + 1u)) + 1u];
		pSrc[(2u * (i + 1u)) + 1u] = pSrc[(2u * (j + fftLenBy2)) + 1u];
		pSrc[(2u * (j + fftLenBy2)) + 1u] = in;

		/*  Reading the index for the bit reversal */
		j = *pBitRevTable;

		/*  Updating the bit reversal index depending on the fft length */
		pBitRevTable += bitRevFactor;
	}
}



/*
   * @brief  In-place bit reversal function.
   * @param[in, out] *pSrc        points to the in-place buffer of Q15 data type.
   * @param[in]      fftLen       length of the FFT.
   * @param[in]      bitRevFactor bit reversal modifier that supports different size FFTs with the same bit reversal table
   * @param[in]      *pBitRevTab  points to bit reversal table.
   * @return none.
 */

void arm_bitreversal_q15(
    q15_t* pSrc16,
    uint32_t fftLen,
    uint16_t bitRevFactor,
    uint16_t* pBitRevTab)
{
	q31_t* pSrc = (q31_t*) pSrc16;
	q31_t in;
	uint32_t fftLenBy2, fftLenBy2p1;
	uint32_t i, j;

	/*  Initializations */
	j = 0u;
	fftLenBy2 = fftLen / 2u;
	fftLenBy2p1 = (fftLen / 2u) + 1u;

	/* Bit Reversal Implementation */
	for(i = 0u; i <= (fftLenBy2 - 2u); i += 2u) {
		if(i < j) {
			/*  pSrc[i] <-> pSrc[j]; */
			/*  pSrc[i+1u] <-> pSrc[j+1u] */
			in = pSrc[i];
			pSrc[i] = pSrc[j];
			pSrc[j] = in;

			/*  pSrc[i + fftLenBy2p1] <-> pSrc[j + fftLenBy2p1];  */
			/*  pSrc[i + fftLenBy2p1+1u] <-> pSrc[j + fftLenBy2p1+1u] */
			in = pSrc[i + fftLenBy2p1];
			pSrc[i + fftLenBy2p1] = pSrc[j + fftLenBy2p1];
			pSrc[j + fftLenBy2p1] = in;
		}

		/*  pSrc[i+1u] <-> pSrc[j+fftLenBy2];         */
		/*  pSrc[i+2] <-> pSrc[j+fftLenBy2+1u]  */
		in = pSrc[i + 1u];
		pSrc[i + 1u] = pSrc[j + fftLenBy2];
		pSrc[j + fftLenBy2] = in;

		/*  Reading the index for the bit reversal */
		j = *pBitRevTab;

		/*  Updating the bit reversal index depending on the fft length  */
		pBitRevTab += bitRevFactor;
	}
}
